Overview of STIS Repair Plans

Charles R. Proffitt

November 16, 2006

STIS Repair TIPS Presentation Nov 16, 2006 2

STIS History

Installed during SM2, Feb 14, 1997 Side 1 Failed May 16, 2001 (after ~ 4.5 yrs)

Short across power input leads Probably failed tantalum capacitor Side 1 electronics not accessible w/o removing STIS

Side 2 failed Aug 3, 2004 (after ~ 3 yrs) Interpoint converter in low voltage power supply failed Supplied power to most instrument mechanisms -

aperture wheel, MSM, CCD shutter, etc. Can’t get light to the detectors Need to replace LVPS2 card in MEB1 Can be accessed w/o removing STIS

STIS Repair TIPS Presentation Nov 16, 2006 3

STIS in HST with Location of MEB

STISNICMOS

NCC

+V2

MEB Cover

STIS Repair TIPS Presentation Nov 16, 2006 4

STIS

+V2Side

+V3Side

MEB-1

MEB-2

Flight STIS Instrument

MEB-1Cover

L-Handle

EVA Handle

MEB CoverExtension

MEB CoverExtension

Clamp

STIS Closeup

STIS Repair TIPS Presentation Nov 16, 2006 5

STIS Main Electronics Box (MEB)

LVPS-2

LVPS2 Board (Engineering Unit)

MEB1 with Cover Removed

MEB Structure (non-flight)

STIS Repair TIPS Presentation Nov 16, 2006 6

LVPS-2 Interfaces

Circuit board LVPS-2 has 3 main functions Supply Heater Power

+15 volts to Thermal Control Zone A and B Supply Calibration Lamp Power

+30 volts to Calibration Lamp Controller Supply Mechanism Power

+5 volts to Mechanism Optical Coupler +15 volts to Mechanism Drivers +30 Volts to Mechanism motors

LVPS-2R will connect to MEB motherboard

STIS Repair TIPS Presentation Nov 16, 2006 7HST +V2

Functional Overview of RepairMajor activities to be performed to repair STIS

Open the +V2 Aft Shroud doors

Remove STIS EVA Handrail

Remove MEB Cover Clamp

Install the Fastener Capture Plate (FCP) Tool

Release MEB cover fasteners (111)

Remove MEB Cover and FCP Tool

Remove failed LVPS-2 board

Install replacement LVPS-2R board

Install replacement MEB cover

Perform Aliveness Test

Install the STIS Thermal Interface Kit (STIK)

Install the STIK Radiator (STIKER)

Close the +V2 Aft Shroud doors

STIS Repair TIPS Presentation Nov 16, 2006 8

EVA Timeline Goal from STIS Repair SRR was to get STIS repair

and cooling to fit in one EVA day.

STIS Repair TIPS Presentation Nov 16, 2006 9

STIS Repair - NBL 06.2 Images

STIS Repair TIPS Presentation Nov 16, 2006 10

STIS Aliveness Test

To be conducted during EVA Verify connectivity of LVPS-2R board to MEB motherboard. Ensure that major functions of LVPS-2R all work

Verify heaters enabled Enable SES telemetry collection Enable (close) mechanism and lamp relays and verify output voltages

Less Than 10 minutes in duration. Macro started at beginning of test will ensure auto-shutdown

Isolate any failure to specific pin.

(This is when we find out if it worked)

STIS Repair TIPS Presentation Nov 16, 2006 11

Cooling System (SCS) Overview STIS

The STIS Cooling System (SCS) is intended to conduct heat away from the MAMA detector radiator and radiate it into the aft-shroud.

Evolved from the STIK interface to the Aft Shroud Cooling System

Three part assembly: SCS Mounting Bracket (SMB) The STIS Thermal Interface Kit (STIK

An actuator forces STIK pressure plate against STIS radiator

Soft thermal interface material on the pressure plate conducts heat to heat pipes.

The STIK Extended Radiator (STIKER) Spreader heat pipes on the STIKER

conduct and radiate heat away from the instrument.

STISNICMOS

NCC

STIKER

STIK Support Bracket

STIS Repair TIPS Presentation Nov 16, 2006 12

Why install the SCS?

Without SCS would expect a significant increase in MAMA tube temperature over previous side-2 values (~ 4 C).

Substantial increase in MAMA dark rates New temperature regime for detectors SCS should keep tube temperatures ~ 2 C lower than

were seen in 2003-2004. Should reduce MAMA detector dark currents.

STIS Repair TIPS Presentation Nov 16, 2006 13

Challenges of STIS Repair

STIS repair requires a whole EVA If fewer EVAs than expected are available, STIS repair will be the first

thing deleted! Removal of 111 MEB Cover Fasteners

Need to be prepared to handle stripped or jammed fasteners Removal of MEB cover

RFI gasket Removal of LVPS-2 card

Card Locks may stick - studies indicate card can be removed anyway Insertion of LVPS-2R

Tolerances very tight, need all active pins to connect Need enough force to engage pins, but not enough to break anything

Debris generated by fastener, cover plate, and card removal Determined to be within acceptable limits

HST PCS analysis of SCS Jitter and STIKER mass control ongoing Failed SCS installation could cause jitter.

STIS Repair TIPS Presentation Nov 16, 2006 14

Status after PDR

Hardware shown to meet requirements

NBL tests successfully demonstrated execution of STIS Repair with high-fidelity hardware

10 successful completions of LVPS-2 change-out

2 successful completions of SCS installation

Extensive testing and analysis performed to show compliance with HST Contamination requirements

Test results for high-risk tasks (Card Extraction and Insertion) and resulting requirements

The STIS Repair Team has defined and implemented plans, processes, tools, and has in place the organization to proceed to CDR (January 2007).

STIS Repair TIPS Presentation Nov 16, 2006 15

STIS Repair Top-level Schedule

SRR

March May JuneApr May June July Aug Sept Oct Nov Dec Jan Feb

NBL06-02

PDR CDR

Contamination Study

Card Extraction Study

STIS Repair Reqts Dev

EM ManufVibe

Func TestLVPS-2R

MEB Replacement Cover ManufactureMech Verif

ThermalVac

EMIMechanism

Vib Modal

ThermalAcoustic

w/Carriers

STIKER Manufacture Amb Test

STIK

Vibe

T/VModalMechVerif

Glove box

April

200720062006

STIS MEB Sim

STIS Trainer 2 - JSC

ManufactureDesign

Manufacture

Manufacture

STIS Trainer 1 - STAR

Design

Crew FAM 1

STIS Repair System

SRRMPT CDR

CATSSTIS CATS

PDR

Peer Review 2

MPT PDR

Peer Review 1

Fl ManufPWB Flatness

Func Test

PeerReview

ManufactureAmb Test

Vibe

July

Interpoints replaced & COS testing complete

PER

PeerReview

EMC

STIS CATS CDR